Boston Consulting Group (BCG) has released its first Brand Advocacy Index (BAI) to measure the impact of word-of-mouth recommendations on brands.

This new report reveals that brands with high levels of advocacy significantly outperform companies that receive negative word-of-mouth. On average, the highest scoring brands in this report saw 27 percent points sales growth ahead of their lowest-scoring peers.

At 50 percent, non luxury automobiles have a leading average BAI score, ahead of brands in smartphones (46 percent), grocery (24 percent), mobile telecommunication (20 percent) and retail banking (10 percent). The most recommended brands in each industry are Volkswagen & Toyota, iPhone, Mercadona, Free and First Direct.

Volkswagen, the highest rated brand, has earned word-of-mouth recommendations across multiple countries. However, some brands make the list due to specific drivers of advocacy that matter more in one market. Take, for instance, Trader Joe’s 49 percent in the U.S. and Free, a French mobile company, owning 50 percentage points in France.

“Although the level of advocacy varies widely by industry and country, we have not found a single category in which advocacy is irrelevant,” Pedro Esquivias, a BCG partner and coauthor of the report, said in the press release.

The BAI indicates that proactive companies start adding brand advocacy to their traditional marketing mix in order to build long-term relationships, not just social media buzz.

BCG surveyed more than 32,000 consumers in the U.S., U.K., France, Germany and Spain. Get the full report from BCG.